.\" Copyright (c) 2003
.\"	Bill Paul <wpaul@windriver.com>. All rights reserved.
.\"
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.\" modification, are permitted provided that the following conditions
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.\"    must display the following acknowledgement:
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.Dd November 7, 2022
.Dt RE 4
.Os
.Sh NAME
.Nm re
.Nd "RealTek 8139C+/8169/816xS/811xS/8168/810xE/8111 PCI/PCIe Ethernet adapter driver"
.Sh SYNOPSIS
To compile this driver into the kernel,
place the following lines in your
kernel configuration file:
.Bd -ragged -offset indent
.Cd "device miibus"
.Cd "device re"
.Ed
.Pp
Alternatively, to load the driver as a
module at boot time, place the following line in
.Xr loader.conf 5 :
.Bd -literal -offset indent
if_re_load="YES"
.Ed
.Sh DESCRIPTION
The
.Nm
driver provides support for various NICs based on the RealTek RTL8139C+,
RTL8169, RTL816xS, RTL811xS, RTL8168, RTL810xE and RTL8111 PCI and
PCIe Ethernet controllers.
.Pp
NICs based on the 8139C+ and 810xE are capable of 10 and 100Mbps speeds
over CAT5 cable.
NICs based on the 8169, 816xS, 811xS, 8168 and 8111 are capable of 10, 100
and 1000Mbps operation.
.Pp
All NICs supported by the
.Nm
driver have TCP/IP checksum offload and hardware VLAN tagging/insertion
features, and use a descriptor-based DMA mechanism.
They are also
capable of TCP large send (TCP segmentation offload).
.Pp
The 8139C+ is a single-chip solution combining both a 10/100 MAC and PHY.
The 8169 is a 10/100/1000 MAC only, requiring a GMII or TBI external PHY.
The 816xS, 811xS, 8168 and 8111 are single-chip devices containing both a
10/100/1000 MAC and 10/100/1000 copper PHY.
Standalone 10/100/1000 cards are available
in both 32-bit PCI and 64-bit PCI models.
The 8110S is designed for
embedded LAN-on-motherboard applications.
.Pp
The 8169, 8169S and 8110S also support jumbo frames, which can be configured
via the interface MTU setting.
The MTU is limited to 7422, since the chip cannot transmit larger frames.
Selecting an MTU larger than 1500 bytes with the
.Xr ifconfig 8
utility configures the adapter to receive and transmit jumbo frames.
.Pp
The
.Nm
driver supports the following media types:
.Bl -tag -width ".Cm 10baseT/UTP"
.It Cm autoselect
Enable autoselection of the media type and options.
The user can manually override
the autoselected mode by adding media options to
.Xr rc.conf 5 .
.It Cm 10baseT/UTP
Set 10Mbps operation.
The
.Xr ifconfig 8
.Cm mediaopt
option can also be used to select either
.Cm full-duplex
or
.Cm half-duplex
modes.
.It Cm 100baseTX
Set 100Mbps (Fast Ethernet) operation.
The
.Xr ifconfig 8
.Cm mediaopt
option can also be used to select either
.Cm full-duplex
or
.Cm half-duplex
modes.
.It Cm 1000baseTX
Set 1000baseTX operation over twisted pair.
The RealTek gigE chips support 1000Mbps in
.Cm full-duplex
mode only.
.\" .It Cm 1000baseSX
.\" Set 1000Mbps (Gigabit Ethernet) operation.
.\" Both
.\" .Cm full-duplex
.\" and
.\" .Cm half-duplex
.\" modes are supported.
.El
.Pp
The
.Nm
driver supports the following media options:
.Bl -tag -width ".Cm full-duplex"
.It Cm full-duplex
Force full duplex operation.
.It Cm half-duplex
Force half duplex operation.
.El
.Pp
For more information on configuring this device, see
.Xr ifconfig 8 .
.Sh HARDWARE
The
.Nm
driver supports RealTek RTL8139C+, RTL8169, RTL816xS, RTL811xS, RTL8168,
RTL810xE and RTL8111 based Fast Ethernet and Gigabit Ethernet adapters including:
.Pp
.Bl -bullet -compact
.It
Alloy Computer Products EtherGOLD 1439E 10/100 (8139C+)
.It
Compaq Evo N1015v Integrated Ethernet (8139C+)
.It
Corega CG-LAPCIGT Gigabit Ethernet (8169S)
.It
D-Link DGE-528(T) Gigabit Ethernet (8169S)
.It
Gigabyte 7N400 Pro2 Integrated Gigabit Ethernet (8110S)
.It
LevelOne GNC-0105T (8169S)
.It
LinkSys EG1032 (32-bit PCI)
.It
PLANEX COMMUNICATIONS Inc.\& GN-1200TC (8169S)
.It
TP-Link TG-3468 v2 Gigabit Ethernet (8168)
.It
USRobotics USR997902 Gigabit Ethernet (8169S)
.It
Xterasys XN-152 10/100/1000 NIC (8169)
.El
.Sh LOADER TUNABLES
Tunables can be set at the
.Xr loader 8
prompt before booting the kernel or stored in
.Xr loader.conf 5 .
.Bl -tag -width "xxxxxx"
.It Va hw.re.intr_filter
This tunable makes driver use interrupt filter handler on
controllers that support MSI/MSI-X capability.
If MSI/MSI-X is disabled by administrator this tunable has no
effect and driver will use interrupt filter handler.
The default value is 0 to use interrupt thread handler.
.It Va hw.re.msi_disable
This tunable disables MSI support on the Ethernet hardware.
The default value is 0.
.It Va hw.re.msix_disable
This tunable disables MSI-X support on the Ethernet hardware.
The default value is 0.
.It Va hw.re.prefer_iomap
This tunable controls which register mapping should be used on the
specified device.
A non-zero value enables I/O space register mapping.
The default value is 0 to use memory space register mapping.
.El
.Sh SYSCTL VARIABLES
The following variables are available as both
.Xr sysctl 8
variables and
.Xr loader 8
tunables:
.Bl -tag -width "xxxxxx"
.It Va dev.re.%d.int_rx_mod
Maximum amount of time to delay receive interrupt processing in
units of 1us.
The accepted range is 0 to 65, the default is 65(65us).
Value 0 completely disables the interrupt moderation.
The interface need to be brought down and up again before a change
takes effect.
.El
.Sh DIAGNOSTICS
.Bl -diag
.It "re%d: couldn't map memory"
A fatal initialization error has occurred.
.It "re%d: couldn't map ports"
A fatal initialization error has occurred.
.It "re%d: couldn't map interrupt"
A fatal initialization error has occurred.
.It "re%d: no memory for softc struct!"
The driver failed to allocate memory for per-device instance information
during initialization.
.It "re%d: failed to enable memory mapping!"
The driver failed to initialize PCI shared memory mapping.
This might
happen if the card is not in a bus-master slot.
.It "re%d: no memory for jumbo buffers!"
The driver failed to allocate memory for jumbo frames during
initialization.
.It "re%d: watchdog timeout"
The device has stopped responding to the network, or there is a problem with
the network connection (cable).
.El
.Sh SEE ALSO
.Xr altq 4 ,
.Xr arp 4 ,
.Xr miibus 4 ,
.Xr netintro 4 ,
.Xr ng_ether 4 ,
.Xr polling 4 ,
.Xr rgephy 4 ,
.Xr vlan 4 ,
.Xr ifconfig 8
.Rs
.%T RealTek Semiconductor RTL8139C+, RTL8169, RTL8169S and RTL8110S datasheets
.%U https://www.realtek.com
.Re
.Sh HISTORY
The
.Nm
device driver first appeared in
.Fx 5.2 .
.Sh AUTHORS
The
.Nm
driver was written by
.An Bill Paul Aq Mt wpaul@windriver.com .
.Sh BUGS
The Xterasys XN-152 32-bit PCI NIC, which uses the RTL8169 MAC and
Marvell 88E1000 PHY, has a defect that causes DMA corruption
if the board is plugged into a 64-bit PCI slot.
The defect
lies in the board design, not the chip itself: the PCI REQ64# and ACK64#
lines should be pulled high, but they are not.
The result is that the
8169 chip is tricked into performing 64-bit DMA transfers even though
a 64-bit data path between the NIC and the bus does not actually exist.
.Pp
Unfortunately, it is not possible to correct this problem in software,
however it is possible to detect it.
When the
.Nm
driver is loaded, it will run a diagnostic routine designed to
validate DMA operation by placing the chip in digital loopback mode
and initiating a packet transmission.
If the card functions properly,
the transmitted data will
be echoed back unmodified.
If the echoed data is corrupt, the driver
will print an error message on the console and abort the device attach.
The
user should ensure the NIC is installed in a 32-bit PCI slot to
avoid this problem.
.Pp
The RealTek 8169, 8169S and 8110S chips appear to only be capable of
transmitting jumbo frames up to 7.5K in size.
.Pp
If this driver is causing problems then an updated driver from
the vendor can be found in ports under net/realtek-re-kmod.
